Lipases have been widely used for esterification of various carboxylic acids such as fatty acids with alcohols such as monoalcohols or polyhydric alcohols and for transesterification between a plurality of carboxylic acid esters. Among those reactions, transesterification is an important technology employed primarily for the modification of animal and vegetable oils and fats and as a method for the manufacture of esters of various fatty acids, sugar esters, or steroids. If a lipase, which is an oils and fats hydrolase, is used as a catalyst for those reactions, the transesterification can be conducted under thermally mild conditions of room temperature to about 70° C., and side reactions can be inhibited and energy cost can be reduced by comparison with the conventional chemical reactions. Moreover, because the lipase serving as a catalyst is a natural product, safety is high. Furthermore, the target product can be manufactured with good efficiency by the mass specificity or position specificity thereof However, if a lipase powder is directly used for transesterification, sufficient activity thereof cannot be demonstrated and it is inherently difficult to disperse a water-soluble lipase in oily starting materials and the recovery thereof is also difficult. For this reason, the lipase has been generally used for esterification or transesterification after immobilizing it on a support, for example, an anion-exchange resin (Patent Document 1), a phenol-adsorbed resin (Patent Document 2), a hydrophilic support (Patent Document 3), a cation-exchange resin (Patent Document 4), and a chelate resin (Patent Document 5).
Lipase has thus been conventionally used for transesterification in an immobilized form, but the immobilizing treatment conducted to obtain such an immobilized lipase resulted in loss of activity inherent to lipase. Moreover, when a porous substrate was used, the pores were clogged by the starting material or reaction products which resulted in the decreased transesterification ratio. Furthermore, in the conventional transesterification reactions using immobilized lipase, moisture held by the support was introduced into the reaction system. As a result, side reactions, for example, the formation of diglycerides or monoglycerides in the transesterification of oils and fats was difficult to avoid.
In light of the foregoing circumstances, a variety of technologies using lipase powders have been developed. For example, there was suggested a method for conducting transesterification in which a lipase powder was dispersed in a starting material containing an ester so that 90% or more of the particles of the dispersed lipase powder had a particle size within a range of 1 to 100 μm during transesterification in the presence or absence of an inert organic solvent (Patent Document 6). Furthermore, it was also suggested to use an enzyme powder obtained by drying an enzyme solution containing a phospholipid or a lipophilic vitamin (Patent Document 7).
However, a lipase powder with even higher lipase activity is desired.    Patent Document 1: Japanese Patent Application laid-open No. S60-98984    Patent Document 2: Japanese Patent Application Laid-open No. S61-202688    Patent Document 3: Japanese Patent Application Laid-open No. H2-138986    Patent Document 4: Japanese Patent Application Laid-open No. H3-61485    Patent Document 5: Japanese Patent Application Laid-open No. H1-262795    Patent Document 6: Japanese Patent No. 2668187    Patent Document 7: Japanese Patent Application Laid-open No. 2000-106873